Controlled Synthesis of Atomically Thin 1T-TaS₂ for Tunable Charge Density Wave Phase Transitions

The charge density wave (CDW) in two-dimensional (2D) materials is attracting substantial interest because of its magnificent many-body collective phenomena. Various CDW phases have been observed in several 2D materials before they reach the phase of superconductivity. However, to date, the atomically thin CDW materials were mainly fabricated by mechanically exfoliating from their bulk counterparts, which leads to low production yield and small sample sizes. Here, we report the controlled synthesis of atomically thin 1T-TaS₂, a typical CDW material, by a chemical vapor deposition (CVD) method. The high quality of as-grown 1T-TaS₂ has been confirmed by complementary characterization technologies. Moreover, the thickness-dependent CDW phase transitions have been revealed in these ultrathin flakes by temperature-dependent Raman spectra. This work opens up a new window for the large-scale synthesis of ultrathin CDW materials and sheds light on the fabrication of next-generation electronic devices.